How would you test for assortative mating between benthic and limnetic ecotypes?

How would you test for assortative mating between benthic and limnetic ecotypes?

• A. Conduct mate-choice experiments or use genetic parentage analysis to see if individuals preferentially mate with same ecotype.
• B. Assortative mating cannot be detected in controlled crosses.
• C. Assortative mating is inferred from color variation alone.
• D. Assortative mating requires reciprocal transplant experiments.

Answer: (C)

Testing for assortative mating focuses on who mates with whom, not just how individuals look. To really know if benthic and limnetic sticklebacks prefer mates from their own ecotype, you need evidence of mate choice or of actual parentage patterns. In a mate-choice setup, you present a focal fish with potential partners from both ecotypes and observe which one it chooses, which directly reveals any preference for the same ecotype. Another solid approach is genetic parentage analysis: by genotyping offspring and assigning parents, you can see whether matings occur more often within the same ecotype than expected by chance. Relying on color variation alone won’t establish mating preferences, because color differences might correlate with ecotype without reflecting actual mate choice. Reciprocal transplant experiments address how fitness varies across habitats rather than mating decisions. And controlled crosses can indeed reveal assortative mating by showing whether cross-ecotype matings occur less frequently than expected, so that option isn’t the right way to measure mate preference on its own.

Testing for assortative mating focuses on who mates with whom, not just how individuals look. To really know if benthic and limnetic sticklebacks prefer mates from their own ecotype, you need evidence of mate choice or of actual parentage patterns. In a mate-choice setup, you present a focal fish with potential partners from both ecotypes and observe which one it chooses, which directly reveals any preference for the same ecotype. Another solid approach is genetic parentage analysis: by genotyping offspring and assigning parents, you can see whether matings occur more often within the same ecotype than expected by chance.

Relying on color variation alone won’t establish mating preferences, because color differences might correlate with ecotype without reflecting actual mate choice. Reciprocal transplant experiments address how fitness varies across habitats rather than mating decisions. And controlled crosses can indeed reveal assortative mating by showing whether cross-ecotype matings occur less frequently than expected, so that option isn’t the right way to measure mate preference on its own.